46,XX testicular difference of sexual development (DSD)
Folks with the 46,XX testicular difference of sexual development (DSD) are genetically female, but look (and feel) like males in every other way.
Reifenstein syndrome
Reifenstein syndrome is an androgen insensitivity syndrome occurring in foetal development that results in improper sex organ development in boys.
5-alpha-reductase deficiency (5 ARD)
5 ARD is a genetic blip that blocks the conversion of testosterone to dihydrotestosterone (DHT) in a growing foetus. DHT is required for the penis and testicles to develop in a male foetus, resulting in ambiguous genitalia. People with 5 ARD may be brought up as girls or boys.
Complete, mild, or partial androgen insensitivity syndrome (CAIS, MAIS, PAIS)
Androgen insensitivity syndromes mean babies born as genetic males have an androgen receptor problem that means they develop, more or less, into females, including gender identity, body shape, and sexual identity.
Variations in genitalia
Variations in genitalia can be seen on a new baby that don't match either a typical boy or girl, requiring further investigations.
Congenital adrenal hyperplasia (CAH)
Congenital adrenal hyperplasia (CAH) is an adrenal gland disorder where the production of cortisol is affected by an enzyme defect. Androgen precursors accumulate in the blood, with results that range from salt-wasting, high blood pressure, and virilising/feminising.
The Prader Scale of genitalia explained
The Prader Scale shows human genitalia from 0 to 6, from typically female at one end to typically male.
Clitoromegaly
Large clitorises can develop for several reasons, with the most common being an excess of androgens for some reason when a foetus was developing.